Rob I had both for sale ...just sold both this month ($50 for the KAB4, even posted it on the LBG

).
I have used both. The KAB4 is a jet engine, 30 psi regulator and you know when it is on. It is surprisingly controllable at low settings for so much BTU. Mine was modified so a keg would be cradled and held in place, but it was still very low to the ground.
I still have a SQ14, 15 PSI regulator and is a nice burner. Mine sat outside for several years in the weather. Cleaned out the spiders (I have no idea why, but spiders love to nest inside propane plumbing/burners) and it fired right up. Use mine for frying food. Over 15 gallons it is a bit noticeable the time to boil compared to the KAB4 (duh...200,000 vs 50,000). It is a nice height off the ground and is rock solid stable.
If you are planning on doing larger batches or heating an HLT, I would spend the extra $30 and get the KAB4.
Jason